In order to filter, for example, in the automotive field, fluids such as fuels, operating media or passenger compartment air, folded or pleated nonwoven filter materials are frequently used. In this connection, it is often required to connect various edges or end sections of these flat filter materials with each other. Known filter elements are manufactured, for example, from initially zigzag-folded filter material sheets that are shaped to a tubular body. In order to close the tubular body, terminal fold sections must then be fluid-tightly connected to each other.
In the past, in this connection metal clips or clamps, for example, were used that hold together two flat sections resting on each other. It is also common to adhesively connect the two filter material sheets with each other or to connect them by fusing. In particular in case of multi-layer filter media, for example, several layers of thin nonwoven material that is impregnated or comprises special intermediate layers, it is difficult to prevent fraying of the edges that are resting on each other. A special difficulty resides in that the flat media to be connected must be connected fluid-tightly, i.e., the fluid to be filtered may not pass unfiltered at the connecting location through the filter material.